Such appliances are known, and they enable various attachments such as chopping blades, grating and shredding disks, liquidizers etc. to be mounted inside a bowl, the attachments being rotated inside the bowl by an electric motor disposed in a base and having its shaft projecting into the bowl.
In certain household food processors, such as the one described in Patent FR-A-2 147 361 (Verdun), the motor is housed in a base, with the bowl being mounted on the base and therefore above the motor. The bottom of the bowl surrounds a base plate provided with lugs which are inserted into grooves when the bowl is mounted on the base, so that the bowl is held stationary in a determined position on the base.
It is essential for consumer appliances to be provided with safety means designed to prevent injuries to users. Such means are designed to prevent any contact between the hands of the user and an attachment that is rotating. Therefore, the appliance must be capable of operating only when the bowl is closed by its lid, the foodstuffs to be processed then being inserted into the bowl via a feed tube through which neither a hand nor even a finger can pass.
In the above-mentioned patent, such safety means are obtained by a safety rod which enables the appliance to operate, i.e. which enables the motor to be started, only when the bowl is properly attached to the base, and when the lid closing the bowl is in the closed position. In this way, it is impossible for there to be any contact between the hands of the user and an attachment that is rotating. In that known device, the push-rod, which is vertically movable under the action of a spring and of a cam provided on the lid, extends along a channel formed along a generator line of the cylindrical bowl. The spring is mounted in the bottom portion of the channel extending along a generator line of the cylindrical bowl. The spring automatically returns the push-rod to the high position as soon as the cam is released, thereby closing the switch for starting the motor.
The switch for starting the motor is included in the base. This means that the bottom portion of the push-rod has to pass through the top surface of the base so as to come into contact with the switch. The base is provided with a hole for that purpose. To prevent splashes of liquid from ingressing into the base, which could cause the motor to be damaged so that it no longer operates correctly, the hole is commonly shut off by a flexible membrane which becomes deformed under pressure from the push-rod, thereby enabling the push-rod to press against the control member of the switch.
Unfortunately, liquid, semi-liquid, or powder substances may be deposited on the membrane inside the hole in the base, and they may work their way down inside the base and into the electrical circuit, with the protective means then becoming less effective.